Page 1 Storminess in Northern Italy, the Adriatic Sea and a comparison to some other EU areas Christoph Matulla Central Institute for Meteorology and Geodynamics, Austria Environment Canada, Toronto, Canada Hans von Storch Institute for Coastal Research, GKSS Research Center, Germany and KlimaCampus Hamburg, Germany 27 October 2008, CORILA meeting in Venice

1851 foundation of the Austrian weather service, since 1872 located at Hohe Warte 38, architect: Johann Heinrich Freiherr von Ferstel 1873 foundation of the International Meteorological Organization (IMO) in Vienna -- precurser organization of the WMO

Page 3 6% flood 0,25% tsunami 6,25% earthquake 11% severe storm 4% tornado 3% hail 1% other storms 1% flash flood 2,5% winter damage, frost 2% wildfire 6,5% 81% 7% 5,5% 1 % heat wave, drought Overall losses: US$ 1,700bn* Insured losses: US$ 400bn* 3% wildfire 29% tropical storm 6% winter storm, blizzard 1% other storms 1% flash flood 7% heat wave, drought 2% winter damage, frost 23% flood 19% earthquake <1% volcanic activity 5% severe storm 20% 44% 24% 12% 49% tropical storm 13% winter storm, blizzard 1% tsunami 1% hail 2% tornado <1% landslide *original values Natural disasters Percentage distribution worldwide © 2007 NatCatSERVICE, Geo Risks Research, Munich Re Taken from a presentation given by Mr Berz in Innsbruck at a COST meeting (2008)

Page 4 What is happening to extratropical storminess? Is it presently evolving outside its range of natural variability? At first sight this question appears to be best answered by the help of wind statistics, but wind time series are almost always inhomogeneous too short Storminess in Northern Italy, the Adriatic sea and a comparison with some other areas

Page 5 One example from Vienna

Page 6 Pressure based proxies are one way to assess storminess (WASA, 1998) Air pressure readings are usually homogenous and extend far back in time (pressure measurements are the ‘flagship’ of the meteorological measuring program) Storm-proxies may be: Annual/seasonal percentiles of geostrophic wind derived from triangles of pressure readings (e.g., 95 or 99%iles); such percentiles of geostrophic wind and of “real” wind are linearly related. frequency of events with geostrophic wind equal or larger than 25 m/s frequency of 24 hourly local pressure change of 16 hPa in a year frequency of pressure readings less than 980 hPa in a year Hovmöller diagrams

Page 7 Northern Italy and the Adriatic Sea What it is about

Page 8 Data across southern Europe are retrieved from 21 year Gaussian filtered normalized Southern European data were downloaded from the European Climate Assessment & Dataset homepage

Homöller diagrams of seasonal pressure Hvar Page 9

The same for the Page 10

Percentiles of daily pressure readings Lugano Page 11

TENDENCIES Page 12

Percentiles of daily pressure Gospic Page 13

Gospic‘s tendencies Page 14

What‘s up? There is remarkable variablity within the pressure readings and their tendencies on a decadal timescale or so. The Hovmöller diagrams reveal not much change in strom proxies over the past century. That doesn‘t mean that there is no change ahead. It simply says that presently we don‘t experience a change in the storm climate triggered by climate change. Climate change is distinct in thermic parameters (continental temperatures, extention of sea ice, sea level, glacier retreat, etc.) but not conveyed in storminess right now. Do we have to fear powerful changes? Regarding storminess it doesn‘t look like this. Page 15

Page 16 What‘s out there in other areas? How does the Italian result match with other regions in Europe? Relevant publications 99%iles of annual geostrophic wind speeds for a series of station triangles in the North Sea regions and in the Baltic Sea region. Alexandersson et al., 2002

Page 17 Putting geo-wind stories across Europe together

OEKT-10, Wien What may happen in the future? RCAO/ECHAM4 RCAO/HadAM3H A2 Szenario IPCC 2007

Page 19 Conclusion 1.Monitoring extra-tropical storminess may be based on air pressure proxies. 2.This allows assessments for 100 and more years, which is essential. 3.Decades long upward and downwards trends have been detected. 4.These trends are not sustained and have shown recent reversals in all considered regions. 5.Recent trends are not beyond the range of natural variations, as given by the historical past, but are more of intermittent character. Regional temperatures rose significantly at the same time. 6.In N Europe the present absence of a detectable signal is consistent with RCM simulations. 7.In C Europe a positive trend to average storminess is to be observed 8.The areas we looked on in Europe show no significant change in storminess there seems to be no significant tend.

Page 20 N Europe storminess Relevant publications Schmidt, H. and H. von Storch, 1993: German Bight storms analyzed. - Nature 365, 791 Alexandersson, H., T. Schmith, K. Iden and H. Tuomenvirta, 1998: Long-term trend variations of the storm climate over NW Europe. The Global Atmos. Oc. System 6, WASA, 1998: Changing waves and storms in the Northeast Atlantic? - Bull. Amer. Met. Soc. 79, Bärring, L. and H. von Storch, 2004: Northern European Storminess since about Geophys. Res. Letters 31, L20202, doi: /2004GL020441, 1-4 Rockel, B., and K. Woth, 2007: Future changes in near surface wind extremes over Europe from an ensemble of RCM simulations. Climate Change, /s y Matulla, C., W. Schöner, H. Alexandersson, H. von Storch, and X.L. Wang, 2007: European Storminess: Late 19th Century to Present, Climate Dynamics DOI /s y The BACC author team, 2008: Assessment of Climate Change in the Baltic Sea Basin, Springer Verlag Berlin - Heidelberg; ISBN , 473 pp von Storch, H., and R. Weisse, 2008: Regional storm climate and related marine hazards in the Northeast Atlantic, In Diaz, H.F. and Murnane, R.J. (eds.), Climate Extremes and Society, Cambridge: Cambridge University Press (in press) Matulla, C., and H. von Storch, 2008: Changes in Eastern Canadian Storminess since under revision

OEKT-10, Wien Shall we pay more money to insurance companies?